1. Field of the Invention
This invention relates to a device for accurately delivering a ballistically stable, monolothic projectile at repeatable velocities to a specified target using an explosive event without causing fragmentation, deformation, or alteration of the geometric shape of the projectile. Propelling a projectile using high explosives in such a manner is a new principal. In its most preferred embodiment, the invention will deliver a projectile using an explosive event without substantial deformation of the projectile. This invention was specifically developed as a preferred device to disable and render safe the firing train of the fuze mechanism of unexploded ordnance (UXO) to dispose of the UXO more safely.
2. Description of the Related Art
2.1 Propellant Technology
Prior to this invention, propellants were used to launch a projectile. Propellants, which are engineered to maintain a stable burning surface when confined, produce their energy in the form of gas, which is then used within a pressure vessel to propel a projectile. The rate of regression of a burning propellant surface is on the order of inches per second; this is in contrast to chemical reaction that progresses through detonating explosives at a rate exceeding the supersonic speed (i.e., faster than the speed of speed of sound) in the reaction zone. This transient pressure pulse that propagates as a supersonic velocity is termed shock wave. Typically, explosives react on the order of kilometers per second causing a sudden, almost instantaneous release of rapidly expanding hot gases, pressure, and heat creating a shock. In order to deliver a projectile without deforming or fragmenting that projectile, the current state of the art requires the use of propellants confined within a pressure vessel, such as a standard gun. In such a system, as the propellant burns, gas is released in a confined pressure vessel; this gas pressure is the source of mechanical energy which pushes or propels a projectile. Typically, a projectile is placed in a barrel, generally made of high-strength steel, with a propellant powder charge behind the projectile in a closed chamber. Upon initiation, the propellant burns, generating gas, which causes pressure to build on the rear of the projectile, propelling it down the barrel at increasing velocity. In order to conserve momentum, the gun barrel is propelled in a direction opposite to the projectile. This phenomenon is commonly termed recoil. The final velocity of the projectile is controlled by the amount and type of propellant charge used and the length and strength of confinement of the barrel.
2.2 Military Disposal of UXO
The military often must dispose of UXO such as mines and live ammunition under difficult conditions. In order to safely dispose of UXO, the firing train of the UXO must be jammed, removed or interrupted (disrupted) in order to render it safe, thus precluding its detonation or explosive functioning. The current method uses a gun system to drive a low velocity (650 foot per second or lower) projectile into the fuze mechanism, jamming the firing train components or interrupting/moving the firing train components out-of-line such that they can not function the UXO as designed. The firing train consists of combustible and explosive elements arranged in order of decreasing sensitivity. A fuze explosive train may consist of a primer, a detonator, a delay, a relay, a lead and a booster charge used in combination to generate suitable energy to actuate the main charge. The momentum (velocity and mass dependant) of the projectile must be of a sufficient magnitude to effectively penetrate and disrupt the fuze by move the fuzing train/component(s) out-of-line or to decapitate the fuze from the UXO components without initiating an energetic response in the fuzing/initiation train. As such, the projectile velocity must be minimal enough so the shock delivered by the projectile impacting the UXO fuze does not cause an explosive response in the fuze firing train components.
For the above purpose, however, use of a gun system to deliver a projectile is operationally cumbersome and inefficient. Gun systems that deliver a projectile with a velocity sufficient for this purpose have significant recoil. Since any UXO disruption must be initiated remotely to ensure the safety of personnel, a recoil compensation device must be employed to insure the recoil does not alter the aiming of the gun device before the projectile exits the barrel or cause collateral damage to rearward surrounding areas. Also, due to recoil forces and the ricochet potential of the reusable gun components, it is possible to lose the gun components in heavy brush, marsh, and woodland terrain, potentially exposing the operator to unnecessary risks when retrieving components for reuse in areas involving multiple UXO hazards. For UXO firing train disruption purposes, the current state of the art gun systems must be cleaned, loaded, and reassembled, assuming all of the components can be located, and, therefore, are not adapted for rapid UXO clearance conducted under operational conditions. Gun systems are also inherently heavy due to the pressure vessel (barrel and breach) components necessary to contain the operating gas pressure of the gun system.
2.3 Explosive Technology
Currently, explosive energy, which reacts on the order of 1 to 10 km/sec, is generally used to deform material. For instance, current state of the art systems use explosives to deliver material by placing explosives directly in contact with the material. This method directly transfers the explosive impulse to the material, resulting in either the fragmentation or significant deformation of the material. Explosives are used in shaped charges and explosively formed (forged) penetrators (EFPs) to deform thin metal. A shaped charge is an explosive charge with a lined ductile metal cavity having a conical or linear inverted xe2x80x9cVxe2x80x9d shape, specifically designed to produce a high velocity cutting or piercing jet of liner material. As the explosive is detonated it rapidly places high pressure on the liner""s cone apex. The pressure causes the material to go through xe2x80x9chydrodynamic flowxe2x80x9dxe2x80x94as though it were a liquid-although the reaction does not cause it to melt. The resulting jet is a stream of metal particles traveling up to 10 km/sec. Shaped charges are generally used to penetrate their targets by producing a small hole and eroding away the material it collides with. Because the jet is inherently unstable, it particulates and breaks up within a short distance. In an EFP, when the explosive detonates, the liner is severely deformed, inverted (turned inside out), or in some cases collapses and travels at supersonic velocities under 4 km/sec.
Explosives are also used in anti-missile systems warheads and claymore mines to accelerate metal spheres and cubes directly to achieve high velocities. Some deformation of the cubes and spheres is produced. As the sizes of these cubes and spheres are scaled up, the level of deformation increases to the level that severe damage, crushing and fragmentation can be observed. In this method, the material will arrive at the target area in a randomly scattered, spread out fashion.
While the aforementioned methods of delivering materials using an explosive event are sufficient for some applications, they cannot deliver a single, monolithic projectile with the precision and accuracy of the gun system.
This invention uses explosive energy in a fundamentally new fashion. Accordingly, it is the object of this invention to provide a device that, using an explosive event, reproducibly delivers a ballistically stable monolithic projectile to a specified target without deforming or fragmenting that projectile.
It is a further object of this invention to provide a device that delivers a projectile to a specified target without substantial deformation of the projectile using an explosive event.
It is a still further object of this invention to provide a device that has little or no recoil upon initiation, and, therefore, can be readily mounted for deployment.
It is a still further object of this invention to provide a device that can deliver different sized and shaped projectiles at different velocities in order to use the device in numerous applications.
This invention is unique in that it employs an explosive event, rather than traditional pyrotechnic combustion energy confirmed within a pressure vessel, to propel a low velocity projectile, whereby the projectile accounts for the majority of the system weight. This invention is also unique in that all system components, with the exception of the projectile, are consumed, in the explosive event.
The invention described herein can be employed to accelerate a projectile without causing mechanical breakup or significant deformation of the projectile and deliver the projectile, in a reproducible method, to a specific target at a specific velocity.
The invention can be used for many purposes including rendering safe a firing train to more safely disarm or dispose of UXO as previously described.